<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>NaN</title>
	<script>
		/*
			NaN: not a number
		 */
		
		 var res1 = '10' + 20;//1020
		 var res2 = 10*'a';

		 // alert(res2);


		 //var a = 100;

		 var a;
		 a = 100;
	</script>
</head>
<body>
	
</body>
</html>